PCI: tegra: add hot-plug/unplug support

Adds hot-plug/unplug APIs to support dynamic
creation and destruction of PCIe hierarchy of a
respective host controller

Bug 2312016
Bug 200427921

Change-Id: Id8ecef5ab6b2c55543a3c43de2561f47a80fe282
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1819382
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 89 insertions, 0 deletions

diff --git a/drivers/pci/dwc/pcie-tegra.c b/drivers/pci/dwc/pcie-tegra.c
index 90d9b7100..49b353171 100644
--- a/drivers/pci/dwc/pcie-tegra.c
+++ b/drivers/pci/dwc/pcie-tegra.c
@@ -566,6 +566,9 @@ static unsigned int pcie_gen_freq[] = {
 
 static void tegra_pcie_downstream_dev_to_D0(struct tegra_pcie_dw *pcie);
 static int tegra_pcie_dw_pme_turnoff(struct tegra_pcie_dw *pcie);
+static int tegra_pcie_dw_runtime_suspend(struct device *dev);
+static int tegra_pcie_dw_runtime_resume(struct device *dev);
+static int tegra_pcie_dw_link_up(struct dw_pcie *pci);
 
 static inline void dma_common_wr16(void __iomem *p, u32 val, u32 offset)
 {
@@ -1773,6 +1776,80 @@ static int verify_voltage_margin(struct seq_file *s, void *data)
         return 0;
 }
 
+static int __attach_controller(struct tegra_pcie_dw *pcie)
+{
+        int ret;
+
+        if (!pcie->link_state && !pcie->power_down_en) {
+                ret = pm_runtime_put_sync(pcie->dev);
+                if (ret)
+                        return ret;
+        }
+
+        ret = pm_runtime_get_sync(pcie->dev);
+        if (ret)
+                return ret;
+        pcie->link_state = tegra_pcie_dw_link_up(&pcie->pci);
+
+        return 0;
+}
+
+static int __detach_controller(struct tegra_pcie_dw *pcie)
+{
+        if (!pcie->link_state && pcie->power_down_en)
+                return 0;
+
+        return pm_runtime_put_sync(pcie->dev);
+}
+
+/* Enables root port controller and attempts PCIe link up with the device
+ * connected downstream. If link is up, registers host controller with
+ * PCIe sub-system.
+ * @cookie : opaque pointer returned by tegra_pcie_detach_controller() API
+ */
+int tegra_pcie_attach_controller(void *cookie)
+{
+        struct tegra_pcie_dw *pcie = (struct tegra_pcie_dw *)cookie;
+
+        return __attach_controller(pcie);
+}
+EXPORT_SYMBOL(tegra_pcie_attach_controller);
+
+/* Removes PCIe hierarchy of the respective host controller and brings PCIe
+ * link down in a safe way
+ * @pdev: pointer to end point's pci_dev structure
+ * returns a cookie which needs to be passed to
+ * tegra_pcie_attach_controller() API
+ */
+void *tegra_pcie_detach_controller(struct pci_dev *pdev)
+{
+        struct pcie_port *pp = pdev->sysdata;
+        struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+        struct tegra_pcie_dw *pcie = dw_pcie_to_tegra_pcie(pci);
+        int ret;
+
+        ret = __detach_controller(pcie);
+        if (ret)
+                return ERR_PTR(ret);
+
+        return (void *)pcie;
+}
+EXPORT_SYMBOL(tegra_pcie_detach_controller);
+
+static int hot_plug(struct seq_file *s, void *data)
+{
+        struct tegra_pcie_dw *pcie = (struct tegra_pcie_dw *)(s->private);
+
+        return __attach_controller(pcie);
+}
+
+static int hot_unplug(struct seq_file *s, void *data)
+{
+        struct tegra_pcie_dw *pcie = (struct tegra_pcie_dw *)(s->private);
+
+        return __detach_controller(pcie);
+}
+
 #define DEFINE_ENTRY(__name)    \
 static int __name ## _open(struct inode *inode, struct file *file)      \
 {                                                                       \
@@ -1798,6 +1875,8 @@ DEFINE_ENTRY(apply_sbr);
 DEFINE_ENTRY(aspm_state_cnt);
 DEFINE_ENTRY(verify_timing_margin);
 DEFINE_ENTRY(verify_voltage_margin);
+DEFINE_ENTRY(hot_plug);
+DEFINE_ENTRY(hot_unplug);
 
 #ifdef CONFIG_PCIE_TEGRA_DW_DMA_TEST
 static void init_dma_test_debugfs(struct tegra_pcie_dw *pcie)
@@ -1925,6 +2004,16 @@ static int init_debugfs(struct tegra_pcie_dw *pcie)
         if (!d)
                 dev_err(pcie->dev, "debugfs for verify_voltage_margin failed\n");
 
+        d = debugfs_create_file("hot_plug", 0444, pcie->debugfs,
+                                (void *)pcie, &hot_plug_fops);
+        if (!d)
+                dev_err(pcie->dev, "debugfs for hot_plug failed\n");
+
+        d = debugfs_create_file("hot_unplug", 0444, pcie->debugfs,
+                                (void *)pcie, &hot_unplug_fops);
+        if (!d)
+                dev_err(pcie->dev, "debugfs for hot_unplug failed\n");
+
         init_dma_test_debugfs(pcie);
 
         return 0;